Police are hunting for a man who sexually assaulted a cafe worker in Flemington on Sunday.

A male offender allegedly approached a woman while she was working at a cafe in Pin Oak Crescent at about 1pm.

The offender is believed to have spoken to the 23-year-old woman before sexually assaulting her as she walked away.

Police believe the man pictured (above) may be able to assist with their investigation.

Anyone who recognises the man is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report online at crimestoppersvic.com.au